X. 
EXTERNAL APPEARANCE OP GLACIERS. 
Thus far we have examined chiefly the inter- 
nal structure of the glacier ; let us look now at 
its external appearance, and at the variety of cu- 
rious phenomena connected with the deposit of 
foreign materials upon its surface, some of which 
seem quite inexplicable at first sight. Among 
the most striking of these are the large boulders 
elevated on columns of ice, standing sometimes 
ten feet or more above the level of the glacier, 
and the sand-pyramids, those conical hills of 
sand which occur not infrequently on the larger 
Alpine glaciers. One is at first quite at a loss 
to explain the presence of these pyramids in the 
midst of a frozen ice-field, and yet it has a very 
simple cause. 
I have spoken of the many little rills arising 
on the surface of the ice in consequence of its 
melting. Indeed, the voice of the waters is rarely 
still on the glacier during the warm season, ex- 
cept at night. On a summer’s day, a thousand 
streams are born before noontide, and die again 
